Increase in molecular weight of polycondensates

ABSTRACT

An increase in the molecular weight of virgin polycondensates and polycondensate recyclates can be achieved by heating to above the melting point or glass transition temperature and by the addition of diphosphonite.

The present invention relates to a process for increasing the molecularweight of polycondensates and to the polycondensates obtainable by saidprocess.

Polycondensates as exemplified by polyester, polyamide andpolycarbonates are important engineering plastics having many differentutilities, e.g. as foils, bottles, fibres and injection moulding parts.These polymers have in common that they are prepared by polycondensationreactions. The damage done to such polycondensates by processing and useresults mainly in polymer fragments containing functional end groups, asa consequence of chain cleavage reactions.

The mechanical and physical properties depend essentially on themolecular weight of the polymer. Reduced molecular weight makes possibleonly a limited high-quality recycling of used polyesters, polyamides,polycarbonates and production waste, typically generated from fibreproduction and injection moulding, without carrying out anaftertreatment.

It is generally known to enhance the material properties of usedpolycondensates, i.e. polyamides damaged by heat or hydrolysis.Typically these polycondensates can be postcondensated in the solidstate (S. Fakirov, Kunststoffe 74 (1984), 218 and R. E. Grutzner, A.Koine, Kunststoffe 82 (1992), 284). However, this method is timeconsuming and is, moreover, highly sensitive to the impurities that maybe present in waste material.

EP-0 410 230 also proposes the use of phosphoric acid, phosphorous acidor phosphonous acid as catalyst for the solid phase condensation ofpolyamides .

F. Mitterhofer describes investigations using a diphosphonite asprocessing stabiliser for polymer recyclates (C.A. 91, 124534).

It is also commonly known to obtain crosslinked polyamides by using anepoxy resin and a standard polyamide catalyst, preferably sodiumhypophosphite (EP-A-0 295 906). The crosslinked polyamides obtainable inthis manner typically have a melt viscosity which is the four timeshigher than that of the starting polyamide.

Accordingly, it is the object of this invention to provide a processthat makes it possible to increase the molecular weight ofpolycondensates, e.g. polyesters, polyamides and polycarbonates as wellas the corresponding copolymers and blends in a relatively short time.In this process, the increase of the molecular weight shall essentiallybe effected without crosslinking.

Surprisingly, it has been found possible to increase the molecularweight of the polycondensate substantially by fusing and adding at leastone diphosphonite or a mixture of at least one diphosphonite and atleast one difunctional compound to a polycondensate. This molecularweight increase effects an enhancement of the properties of thepolycondensates, e.g. in injection moulding and, in particular, ofrecyclates. With the process of this invention it is possible to achievean increase in the molecular weight of, in particular, polycondensaterecyclates originating from the collection of used technical parts, asfrom automotive and electric utilities, which makes it possible toemploy the recyclates for their original utilities. Such recyclatesoriginate also from, inter alia, industrial or domestic useful materialcollections, production wastes or obligatory returnables.

Accordingly, the invention relates to a process for increasing themolecular weight of polyamides, essentially without crosslinking, whichcomprises heating a polyamide or a copolymer or a blend thereof, withthe addition of at least one diphosphonite to above the melting point(in the case of crystalline polyamides) or to above the glass transitiontemperature (in the case of amorphous polyamides) of the polymer.

Another aspect of the invention is a process for increasing themolecular weight of polycondensate recyclates, essentially withoutcrosslinking, which comprises heating a polyamide recyclate, a polyesterrecyclate or a copolymer or a blend recyclate of these polymers, withthe addition of at least one diphosphonite to above the melting point(in case of crystalline polycondensate types) or to above the glasstransition temperature (in case of amorphous polycondensate types) ofthe polymer.

The invention also relates to a process for increasing the molecularweight of polycondensates, essentially without crosslinking, whichcomprises heating a polyamide, a polyester, a polycarbonate or acopolymer or a blend of these polymers with the addition of at least onediphosphonite and at least one difunctional compound selected from theclass of the diepoxides, bismaleimides, tetracarboxylic dianhydrides,bisoxazolines, bisoxazines, bisacyl lactams or diisocyanates to abovethe melting point (in the case of crystalline polycondensate types) orto above the glass transition temperature (in the case of amorphouspolycondensate types) of the polycondensate.

In addition to polyester, polyamide or polycarbonate, this inventionalso comprises the corresponding copolymers and blends, e.g. PBT/PS,PBT/ASA, PBT/ABS, PET/ABS, PET/PC, PBT/PET/PC, PBT/PET, PA/PP andPA/ABS, as well as mixtures of virgin plastic and recyclate.

Polyamides, ie. virgin polyamides as well as polyamide recyclates, willbe understood as meaning aliphatic and aromatic polyamides orcopolyamides that are derived from diamines and dicarboxylic acidsand/or from aminocarboxylic acids or the corresponding lactams.Illustrative examples of suitable polyamides are:

PA 6, PA 11, PA 12, PA 46, PA 66, PA 69, PA 610, PA 612, as well asamorphous polyamides of the Trogamid PA 6-3-T and Grilamid TR 55 types.Polyamides of the indicated kind are commonly known and commerciallyavailable.

The preferred polyamides in the practice of this invention are PA 6 andPA 6.6 or mixtures thereof, as well as recyclates based thereon.

The polyester, i.e. virgin polyester as well as polyester recyclate, maybe homopolyesters or copolyesters that are derived from aliphatic,cycloaliphatic or aromatic dicarboxylic acids and diols orhydroxycarboxylic acids.

The aliphatic dicarboxylic acids may contain from 2 to 40 carbon atoms,the cycloaliphatic dicarboxylic acids from 6 to 10 carbon atoms, thearomatic dicarboxylic acids from 8 to 14 carbon atoms, the aliphatichydroxycarboxylic acids from 2 to 12 carbon atoms, and the aromatic aswell as the cycloaliphatic hydroxycarboxylic acids from 7 to 14 carbonatoms.

The aliphatic diols may contain from 2 to 12 carbon atoms, thecycloaliphatic diols from 5 to 8 carbon atoms and the aromatic diolsfrom 6 to 16 carbon atoms.

Aromatic diols will be taken to mean those in which two hydroxyl groupsare bonded to one aromatic hydrocarbon radical or to different aromatichydrocarbon radicals.

The polyesters may also be branched with minor amounts, typically 0.1 to3 mol %, based on the dicarboxylic acids, of more than difunctionalmonomers (e.g. pentaerythritol, trimellitic acid,1,3,5-tri(hydroxyphenyl)benzene, 2,4-dihydroxybenzoic acid or2-(4-hydroxyphenyl)-2-(2,4-dihydroxyphenyl)propane).

If the polyesters are based on at least 2 monomers, said monomers may berandomly distributed, or they may be block copolymers.

Suitable dicarboxylic acids are linear and branched saturated aliphaticdicarboxylic acids, aromatic dicarboxylic acids and cycloaliphaticdicarboxylic acids.

Suitable aliphatic dicarboxylic acids are those containing from 2 to 40carbon atoms, typically oxalic acid, malonic acid, dimethylmalonic acid,succinic acid, pimelic acid, adipic acid, trimethyladipic acid, sebacicacid, azelaic acid and dimer acids (dimerisation products of unsaturatedaliphatic carboxylic acids such as oleic acid), alkylated malonic andsuccinic acids such as octadecylsuccinic acid.

Suitable cycloaliphatic dicarboxylic acids are:

1,3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid,1,3- and 1,4-cyclohexanedicarboxylic acid, 1,3- and1,4-(dicarboxylmethyl)cyclohexane, 4,4'-dicyclohexyldicarboxylic acid.

Suitable aromatic dicarboxylic acids are:

preferably terephthalic acid, isophthalic acid, o-phthalic acid, as wellas 1,3-, 1,4-, 2,6- or 2,7-naphthalenedicarboxylic acid,4,4'-diphenyldicarboxylic acid, 4,4'-diphenylsulfonecarboxylic acid,4,4'-benzophenonedicarboxylic acid,1,1,3-trimethyl-5-carboxyl-3-(p-carboxylphenyl)indane, 4,4'-diphenylether dicarboxylic acid, bis-p-(carboxylphenyl)methane orbis-p-(carboxylphenyl)ethane.

The aromatic dicarboxylic acids are preferred, including in particularterephthalic acid and isophthalic acid.

Further suitable dicarboxylic acids are those that contain --CO--NH--groups and which are disclosed in DE-A 2 414 349. Dicarboxylic acidsthat contain N-heterocyclic rings are also suitable, for example thosethat are derived from carboxylalkylated, carboxylphenylated orcarboxybenzylated monoamine-s-triazinedicarboxylic acids (q.v. DE-A 2121 184 and 2 533 675), mono- or bishydantoins, benzimidazolenes orhalogenated benzimidazolenes or parabanic acid. The carboxyalkyl groupsmay contain from 3 to 20 carbon atoms.

Suitable aliphatic diols are the linear and branched aliphatic glycols,preferably those containing from 2 to 12, most preferably from 2 to 6,carbon atoms in the molecule, typically including:

ethylene glycol, 1,2- and 1,3-propylene glycol, 1,2-, 1,3-, 2,3- or1,4-butanediol, pentyl glycol, neopentyl glycol, 1,6-hexanediol,1,12-dodecanediol. A suitable cycloaliphatic diol is conveniently1,4-dihydroxycyclohexane. Further suitable aliphatic diols are typically1,4-bis(hydroxymethyl)cyclohexane, aromatic-aliphatic diols such asp-xylylene glycol or 2,5-dichloro-p-xylylene glycol,2,2-(β-hydroxyethoxyphenyl)propane, as well as polyoxyalkylene glycolssuch as diethylene glycol, triethylene glycol, polyethylene glycol orpolypropylene glycol. The alkylene diols are preferably linear andpreferably contain 2 to 4 carbon atoms.

Preferred diols are the alkylene diols, 1,4-dihydroxycyclohexane and1,4-bis(hydroxymethyl)cyclohexane. Ethylene glycol and 1,4-butanediolare especially preferred.

Further suitable aliphatic diols are the β-hydroxyalkylated, preferablyβ-hydroxyethylated, bisphenols such as 2,2-bis4'-(β-hydroxyethoxy)phenyl!propane. Further bisphenols are mentionedhereinafter.

A further group of suitable aliphatic diols comprises the heterocyclicdiols disclosed in German Offenlegungsschrift specifications 1 812 003,2 342 432, 2 342 372 and 2 453 326. Illustrative examples are:

N,N'-bis(β-hydroxyethyl-5,5-dimethyl)hydantoin,N,N'-bis(β-hydroxypropyl-5,5-dimethyl)hydantoin, methylenebisN-(β-hydroxyethyl)-5-methyl-5-ethylhydantoin!, methylenebisN-(β-hydroxyethyl)-5,5-dimethylhydantoin!,N,N'-bis(β-hydroxyethylbenzylimidazolone, -(tetrachloro)benzimidazoloneor -(tetrabromo)benzimidazolone.

Suitable aromatic diols are mononuclear diphenols and, preferably,dinuclear diphenols which carry a hydroxyl group at each aromaticnucleus. By aromatic are meant preferably aromatic hydrocarbon radicalssuch as phenylene or naphthylene. In addition to e.g. hydroquinone,resorcinol or 1,5-, 2,6 and 2,7-dihydroxynaphthalene, those bisphenolsmerit special mention that may be illustrated by the following formulae:##STR1##

The hydroxyl groups may be in m-position, but are preferably inp-position. R' and R" in this formula may be alkyl of 1 to 6 carbonatoms, halogen such as chloro or bromo and, in particular, hydrogenatoms. A may be a direct bond or --O--, --S--, --(O)S(O)--, --C(O)--,--P(O)(C₁ -C₂₀ alkyl)--, unsubstituted or substituted alkylidene,cycloalkylidene or alkylene.

Unsubstituted or substituted alkylidene is exemplified by:

ethylidene, 1,1- or 2,2-propylidene, 2,2-butylidene, 1,1-isobutylidene,pentylidene, hexylidene, heptylidene, octylidene, dichloroethylidene,trichloroethylidene.

Illustrative examples of unsubstituted or substituted alkylene aremethylene, ethylene, phenylmethylene, diphenylmethylene,methylphenylmethylene. Illustrative examples of cycloalkylidene arecyclopentylidene, cyclohexylidene, cycloheptylidene and cyclooctylidene.

Illustrative examples of bisphenols are:

bis(p-hydroxyphenyl) ether or thioether, bis(p-hydroxyphenyl)sulfone,bis(p-hydroxyphenyl)methane, bis(4-hydroxyphenyl)-2,2-biphenyl,phenylhydroquinone, methylhydroquinone, trimethylhydroqinone,1,2-bis(p-hydroxyphenyl)ethane, 1-phenyl-bis(p-hydroxyphenyl)methane,diphenyl-bis(p-hydroxyphenyl)methane,diphenyl-bis(p-hydroxyphenyl)-methane,bis(3,5-dimethyl-4-hydroxyphenyl)sulfone,bis(3,5-dimethyl-4-hydroxyphenyl)-p-diisopropylbenzene,bis(3,5-dimethyl-4-hydroxyphenyl)-m-diisopropylbenzene,2,2-bis(3',5'-dimethyl-4'-hydroxyphenyl)propane, 1, 1- or2,2-bis(p-hydroxyphenyl)butane,2,2-bis(p-hydroxyphenyl)hexafluoropropane, 1,1-dichloro- or1,1,1-trichloro-2,2-bis(p-hydroxyphenyl)ethane, 1,1-bis(p-hydroxyphenyl)cyclopentane and, preferably,2,2-bis(p-hydroxyphenyl)propane (bisphenol A) and1,1-bis(p-hydroxyphenyl)cyclohexane (bisphenol C).

Suitable polyesters of hydroxycarboxylic acids typically includepolycaprolactone, polypivalolactone or the polyesters of4-hydroxycyclohexanecarboxylic acid or 4-hydroxybenzoic acid.

Also suitable are polymers containing mainly ester bonds, but also otherbonds, such as polyester amides or polyester imides.

Polyesters with aromatic dicarboxylic acids have achieved the greatestimportance, in particular the polyalkylene terephthalates. Inventivemoulding materials are therefore preferred in which the polyester iscomprised of at least 30 mol %, preferably of at least 40 mol %, ofaromatic dicarboxylic acids, and of at least 30 mol %, preferably of atleast 40 mol %, of alkylenediols containing preferably 2 to 12 carbonatoms, based on the polyester.

Especially in this case the alkylenediol is linear and contains 2 to 6carbon atoms and is exemplified by ethylene, trimethylene,tetramethylene or hexamethylene glycol and the aromatic dicarboxylicacid is terephthalic and/or isophthalic acid.

Particularly suitable polyesters are PET, PBT and correspondingcopolymers or blends such as PBT/PC, PBT/ASA, PBT/ABS, PET/ABS, PET/PCor also PBT/PET/PC. PET and the copolymers thereof as well as PBT blendsare particularly preferred.

Polycarbonate (PC) will be taken to mean virgin polycarbonate as well aspolycarbonate recyclate. Polycarbonate (PC) is typically obtained frombisphenol A and phosgene or a phosgene analog such astrichloromethylchloroformate, triphosgene or diphenylcarbonate, in thelast mentioned case by condensation, usually by the addition of asuitable transesterification catalyst, such as a boron hydride, an aminesuch as 2-methylimidazole or a quaternary ammonium salt. In addition tobisphenol A, other additional bisphenol components may be used, and alsomonomers which may be halogenated in the benzene nucleus. Particularlysuitable bisphenol components that merit mention are:

2,2-bis(4'-hydroxyphenyl)propane (bisphenol A),2,4'-dihydroxydiphenylmethane, bis(2-hydroxyphenyl)methane,bis(4-hydroxyphenyl)methane, bis(4-hydroxy-5-propylphenyl)methane,1,1-bis(4'-hydroxyphenyl)ethane, bis(4-hydroxyphenyl)cyclohexylmethane,2,2-bis(4'-hydroxyphenyl)-1-phenylpropane,2,2-bis(3',5'-dimethyl-4'-hydroxyphenyl)propane,2,2-bis(3',5'-dibromo-4'-hydroxyphenyl)propane,2,2-bis(3',5'-dichloro-4'-hydroxyphenyl)propane,1,1-bis(4'-hydroxyphenyl)cyclododecane,1,1-bis(3',5'-dimethyl-4'-hydroxyphenyl)cyclododecane,1,1-bis(4'-hydroxyphenyl)-3,3,5-trimethylcyclohexane,1,1-bis(4'-hydroxyphenyl)--3,3,5,5-tetramethylcyclohexane,1,1-bis(4'-hydroxyphenyl)-3,3,5-trimethylcyclopentane and the bisphenolsindicated above. Furthermore, the polycarbonates may also be branched bysuitable amounts of more than difunctional monomers (examples are asindicated above).

The polycondensate copolymers or blends which may be used in the novelprocess are prepared in conventional manner from the starting polymers.The polyester component is preferably PBT and PET, and the PC componentis preferably a PC based on bisphenol A. The ratio of polyester to PC ispreferably from 95:5 to 5:95. Particularly preferred is a ratio in whichone component constitutes at least 70%.

The invention is of particular importance with respect to polycondensaterecyclates recovered from production waste, useful material collections,or the obligatory returnables originating from, inter alia, theautomotive industry or the electrical sector. The polycondensaterecyclates are damaged by heat and/or hydrolysis in a wide variety ofways. Furthermore, these recyclates may also contain minor amounts ofplastics of different structure such as polyolefins, polyurethanes, ABSor PVC. In addition, these recyclates may also contain as standardimpurities, for example, paint residues, contact media or paint systems,metal traces, water traces, fuel residues, or inorganic salts. In thecase of blends or mixtures, the compatibility may be enhanced by theaddition of compatibilisers.

Diphosphonites according to this invention can be illustrated by formula##STR2## wherein R° is one to five C₁ -C₈ alkyl radicals; X' is aradical ##STR3## and X is a direct bond, --(O)S(O)--, --C(O)--, --S--,--O-- or arylene.

Arylene is typically naphthylene, m-phenylene or p-phenylene.

R° is, in particular, one to three tert-butyl groups or one to threemethyl groups. X' is, in particular, a radical ##STR4## and particularlypreferred a 4,4'-biphenylene radical.

Tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylene-diphosphonite(Irgafos® PEPQ) is very particularly preferred.

It is preferred to use 0.01 to 5 parts, more preferably 0.05 to 2 parts,of a diphosphonite, based on 100 parts of polycondensate.

Difunctional compounds of the class of the diepoxides according to thisinvention may have an aliphatic, aromatic, cycloaliphatic, araliphaticor heterocyclic structure. They contain epoxy groups as side groups orthese groups form part of an alicyclic or heterocyclic ring system. Theepoxy groups are preferably linked to the residual molecule as glycidylgroups through ether or ester bonds, or they are N-glycidyl derivativesof heterocyclic amines, amides or imides. Epoxy resins of these typesare commonly known and commercially available.

The epoxy resins contain two epoxy radicals, typically those of formula##STR5## which radicals are linked direct to carbon, oxygen, nitrogen orsulfur atoms, wherein R₁ and R₃ are both hydrogen, R₂ is hydrogen ormethyl, and n=0, or wherein R₁ and R₃, taken together, are --CH₂ --CH₂-- or --CH₂ --CH₂ --CH₂ --, in which case R₂ is hydrogen and n=0 or 1.

Illustrative examples of epoxy resins are:

I) Diglycidyl and di(β-methylglycidyl) esters which are obtainable byreacting a compound containing two carboxyl groups in the molecule andepichlorohydrin or glycerol dichlorohydrin or β-methyl epichlorohydrin.The reaction is conveniently carried out in the presence of a base.

Compounds containing two carboxyl groups in the molecule may suitably bealiphatic dicarboxylic acids. Exemplary of these dicarboxylic acids areglutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid,sebacic acid or dimerised or trimerised linoleic acid.

Cycloaliphatic dicarboxylic acids may also be used, for exampletetrahydrophthalic acid, 4-methyltetrahydrophthalic acid,hexahydrophthalic acid or 4-methylhexahydrophthalic acid.

Aromatic dicarboxylic acids may also be used, including phthalic acid orisophthalic acid.

II) Diglycidyl or di(β-methylglycidyl) ethers which are obtainable byreacting a compound containing two free alcoholic hydroxyl groups and/orphenolic hydroxyl groups in the molecule with a suitably substitutedepichlorohydrin under alkaline conditions or in the presence of an acidcatalyst and subsequent treatment with an alkali.

Ethers of this type are typically derived from acyclic alcohols such asethylene glycol, diethylene glycol and higher poly(oxyethylene) glycols,1,2-propanediol, or poly(oxypropylene) glycols, 1,3-propanediol,1,4-butanediol, poly(oxytetramethylene) glycols, 1,5-pentanediol,1,6-hexanediol, sorbitol, as well as from polyepichlorohydrins.

They may also be derived from cycloaliphatic alcohols such as 1,3- or1,4-dihydroxycyclohexane, bis(4-hydroxycyclohexyl)methane,2,2-bis(4-hydroxycyclohexyl)propane or1,1-bis(hydroxymethyl)cyclohex-3-ene, or they contain aromatic nuclei,such as N,N-bis(2-hydroxyethyl)aniline orp,p'-bis(2-hydroxyethylamino)diphenylmethane.

The epoxy resins may also be derived from mononuclear phenols, as fromresorcinol, 1,2-benzenediol or hydroquinone, or they are based onpolynuclear phenols such as 4,4'-dihydroxybiphenyl,bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)propane,2,2-bis(3,5-dibromo-4hydroxyphenyl)propane,4,4'-dihydroxydiphenylsulfone, or 9,9-bis(4-hydroxyphenyl)fluorene, oron condensates of phenols with formaldehyde which are obtained underacid conditions, for example phenol novolaks.

III) Bis(N-glycidyl) compounds, obtainable typically bydehydrochlorination of the reaction products of epichlorohydrin withamines which contain two amino hydrogen atoms. These amines aretypically aniline, toluidine, n-butylamine, bis(4-aminophenyl)methane,m-xylylenediamine or bis(4-methylaminophenyl)methane.

The bis(N-glycidyl) compounds, however, also include N,N'-diglycidylderivatives of cycloalkylene ureas such as ethyleneurea or1,3-popyleneurea, and N,N'-diglycidyl derivatives of hydantoins,typically of 5,5-dimethylhydantoin.

IV) Bis(S-glycidyl) compounds, typically bis(S-glycidyl) derivativesthat are derived from dithiols such as 1,2-ethanedithiol orbis(4-mercaptomethylphenyl) ether.

V) Epoxy resins containing a radical of formula X, wherein R₁ and R₃together are --CH₂ --CH₂ --and n is 0, typicallybis(2,3-epoxycyclopentyl) ether, 2,3-epoxycyclopentylglycidyl ether or1,2-bis(2,3-epoxycyclopentyloxy) ethane. Epoxy resins containing aradical of formula X, wherein R₁ and R₃ together are --CH₂ --CH₂ --and nis 1, is typically3,4-epoxy-6-methylcyclohexyl-3',4'-epoxy-6'-methylcyclohexanecarboxylate.

By reason of the preparative process, the above-mentioned difunctionalepoxy resins may contain minor amounts of mono- or trifunctional groups.

Diglycidyl compounds of aromatic structure are mainly used.

It is also possible to use a mixture of epoxy resins of differentstructure.

Trifunctional or polyfunctional epoxy resins may further be added toobtain branched products.

Suitable epoxy resins are typically:

a) liquid diglycidyl ethers of bisphenol A, e.g. Araldit®GY 240,Araldit®GY 250, Araldit®GY 260, Araldit®GY 266, Araldit®GY 2600,Araldit®MY 790;

b) solid diglycidyl ethers of bisphenol A, e.g. Araldit®GT 6071,Araldit®GT 7071, Araldit®GT 7072, Araldit®GT 6063, Araldit®GT 7203,Araldit®GT 6064, Araldit®GT 7304, Araldit®GT 7004, Araldit®GT 6084,Araldit®GT 1999, Araldit®GT 7077, Araldit®GT 6097, Araldit®GT 7097,Araldit®GT 7008, Araldit®GT 6099, Araldit®GT 6608, Araldit®GT 6609,Araldit®GT 6610;

c) liquid diglycidyl ethers of bisphenol F, e.g. Araldit®GY 281,Araldit®GY 282, Araldit®PY 302, Araldit®PY 306;

d) solid polyglycidyl ethers of tetraphenylethane, e.g. CG EpoxyResin®0163;

e) solid and liquid polyglycidyl ethers of phenolformaldehyde novolak,e.g. EPN 1138, EPN 1139,GY 1180, PY307;

f) solid and liquid polyglycidyl ethers of o-cresolformaldehyde novolak,e.g. ECN 1235, ECN 1273, ECN 1280, ECN 1299;

g) liquid glycidyl ethers of alcohols, e.g. Shell® glycidyl ether 162,Araldit®DY 0390, Araldit®DY 0391;

h) liquid glycidyl ethers of carboxylic acids, e.g. Shell®Cardura Eterephthalate, trimellitate, Araldit®PY 284;

i) solid heterocyclic epoxy resins (triglycidylisocyanurate), e.g.Araldit® PT 810;

j) liquid cycloaliphatic epoxy resins, e.g. Araldit®CY 179;

k) liquid N,N,O-triglycidyl ethers of p-aminophenol, e.g. Araldit®MY0510;

l) tetraglycidyl-4-4'-methylenebenzamine orN,N,N',N'-tetraglycidyldiaminophenylmethane, e.g. Araldit®MY 720,Araldit®MY 721.

Particularly preferred difunctional epoxy resins are diglycidyl ethersof bisphenols, typically 2,2-bis(4-hydroxyphenyl)propane (bisphenol A),bis(4-hydroxyphenyl)sulfone (bisphenol S) or mixtures ofbis(ortho-/para-hydroxyphenyl)methane (bisphenol F).

Very particularly preferred difunctional epoxy resins are the soliddiglycidyl ethers of bisphenol A type, e.g. Araldit®GT 6071, GT 7071, GT7072, GT 6097 and GT 6099, the liquid epoxy resins of the bisphenol Ftype, e.g. Araldit GY 281 or PY 306, the liquid glycidyl ethers ofcarboxylic acids, e.g. Shell®Cardura E terephthalate, trimellitate,Araldit®PY 284 and the liquid cycloaliphatic epoxy resins, e.g.Araldit®CY 179.

It is preferred to use 0.01-5 parts, more preferably 0.02-2 parts, ofdiepoxide, based on 100 parts of polycondensate.

Difunctional compounds of the class of the bismaleimides (BMI) accordingto this invention can be illustrated by the following formula (III):##STR6## wherein R is an aliphatic, aromatic, cycloaliphatic orheterocyclic radical; and R' and R" are each independently of the otherhydrogen, C₁ -C₄ alkyl, C₁ -C₆ alkoxy, phenyl or phenyloxy.

The aliphatic, aromatic, cycloaliphatic or heterocyclic radicals containa maximum of 40 carbon atoms. These radicals may be unsubstituted orsubstituted and may also be interrupted by --O--, --S--, --(CH₂)₁₋₆ --,--C(O)--, --P(O)(C₁ -C₁₈ alkyl)-- or --(O)S(O)-- (signifying the radical##STR7## Typical examples of possible substituents are: C₁ -C₁₈ alkyl,C₁ -C₁₈ alkoxy, OH, phenyl and phenyloxy.

R defined as an aliphatic radical is typically a C₁ -C₁₈ polymethyleneradical which may be derived from alkyl radicals such as methyl, ethyl,n-propyl, n-butyl, sec-butyl, tert-butyl, n-hexyl, n-octyl,2-ethylhexyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl,n-tetradecyl, n-hexadecyl or n-octadecyl as well as from furtherbranched isomers.

R defined as an aromatic radical is typically a radical containing 6-40carbon atoms, e.g. phenylene, biphenylene, or naphthylene, or is aphenylene or biphenylene radical linked through one of the groups suchas --O--, --S--, --(CH₂)₁₋₆ --, --C(O)--, --P(O)(C₁ -C₁₈ alkyl)-- or--(O)S(O)--.

R defined as a cycloaliphatic radical is typically a radical containing5-10 carbon atoms, e.g. cyclopentylene, cyclohexylene or cyclooctylene.

R defined as a heterocyclic radical is typically a N-containing 5- or6-membered ring such as pyridylene, pyridazylene or pyrazolylene.

R is preferably an aromatic radical of one of the formulae: ##STR8##wherein X is one of the radicals --CH₂ --, --C(O)--, --P(O)(C₁ -C₁₈alkyl)--, --(O)S(O)--, --O-- or --S--.

R' and R" are preferably each independently of the other hydrogen or C₁-C₄ alkyl. More preferably, R' is hydrogen and R" is hydrogen or methyl.The most preferred meaning of R' and R" is hydrogen.

Very particularly preferred compounds are those of formula ##STR9##

It is preferred to use 0.01-5 parts, more preferably, 0.02-2 parts, ofbismaleinimide, based on 100 parts of polycondensate.

Difunctional compounds of the class of the tetracarboxylic dianhydridesaccording to this invention are those of formula ##STR10## wherein R°°is a radical of formulae (Va)-(Vl) ##STR11## wherein Q is --CH₂ --,--CH(CH₃)--, --C(CH₃)₂ --, --C(CF₃)₂ --, --S--, --O--, --(O)S(O)--,--NHCO--, --CO--or --P(O)(C₁ -C₂₀ alkyl)--, and the aromatic rings informulae (Va)-(Ve) and (Vk) are unsubstituted or substituted by one ormore than one C₁ -C₆ alkyl group, C₁ -C₆ alkoxy group or halogen atom.

The preferred tetracarboxylic dianhydrides are those containing aromaticrings.

It is also possible to use a mixture of tetracarboxylic dianhydrides ofdifferent structure.

It is preferred to use 0.01-5 parts, more preferably 0.02-2 parts and,most preferably, 0.05-1 part, of tetracarboxylic dianhydride, based on100 parts of polycondensate.

Difunctional compounds of the class of the bisoxazolines according tothis invention can be illustrated by formula ##STR12## wherein R₅, R₆,R₇ and R₈ are each independently of one another hydrogen, halogen,alkyl, cycloalkyl, aryl, alkoxy or carboxyalkyl, and X° is anunsubstituted or substituted aromatic radical. X° is preferably abenzene or naphthalene radical.

It is preferred to use 0.01-5 parts, more preferably 0.02-2 parts, ofbisoxazoline, based on 100 parts of polycondensate.

Difunctional compounds of the class of the bisoxazines according to thisinvention may be illustrated by formula ##STR13## wherein R₉, R₁₀, R₁₁,R₁₂, R₁₃ and R₁₄ are each independently of one another hydrogen,halogen, alkyl, cycloalkyl, aryl, alkoxy or carboxyalkyl, and X°° is anunsubstituted or substituted aromatic radical. X°° is preferably abenzene or naphthalene radical.

It is preferred to use 0.01-5 parts, more preferably 0.02-2 parts, ofbisoxazine, based on 100 parts of polycondensate.

Difunctional compounds of the class of the bisacyl lactams according tothis invention can be illustrated by formula ##STR14## wherein q is 1 or2, and Q° is an aromatic radical, typically one of the formulae:##STR15## Wherein X is one of the radicals --CH₂ --, --C(O)--, --P(O)(C₁-C₁₈ alkyl)--, --(O)S(O), --O-- or --S--.

It is preferred to use 0.01-5 parts, more preferably 0.02-2 parts, ofbisacyl lactam, based on 100 parts of polycondensate.

Difunctional compounds of the class of the diisocyanates according tothis invention can be illustrated by formula

    O═C═N--R.sub.15 --N═C═                     (IX),

wherein R₁₅ is C_(1-C) ₂₀ alkylene or polymethylene, arylene, aralkyleneor cycloalkylene.

Preferred diisocyanates are tetramethylenediisocyanate,hexamethylenediisocyanate, dodecamethylenediisocyanate,eicosane-1,20-diisocyanate, 4-butylhexamethylenediisocyanate, 2,2,4- or2,4,4-trimethylhexamethylenediisocyanate, OCN(CH₂)₂ O(CH₂)₂ NCO,toluene-2,4-diisocyanate, p-phenylenediisocyanate,xylylenediisocyanates,3-isocyanatomethyl-3,5,5,5-triethylcyclohexylisocyanate,naphthalenediisocyanates, sulfonyldiisocyanates, 3,3'-, 4,4'- and3,4'-diisocyanates of diphenylmethane, 2,2-diphenylpropane and diphenylether, 3,3'-dimethyl-4,4'-diisocyanatodiphenyl,3,3'-dimethoxy-4,4'-diisocyanatodiphenyl and4,4'-diisocyanatodiphenylmethane. Diisocyanates of aromatic structureare particularly preferred.

However, it is also possible to use diisocyanate generators such aspolymeric urethanes, uretidione dimers and higher oligomers, cyanuratepolymers, urethanes and polymeric urethanes of cyanurate polymers andthermally dissociable adducts of Schiff's bases.

It is preferred to use 0.01-5 parts, more particularly 0.02-2 parts, ofdiisocyanate, based on 100 parts of polycondensate.

It is also possible to use a mixture of different difunctionalcompounds, preferably a mixture of difunctional epoxy resins anddiisocyanates.

In addition to the diphosphonite and the difunctional compound furtherstabilisers may be added to the polycondensate. These furtherstabilisers are known to the skilled person and are selected accordingto the specific demands made of the end product. In particular, it ispossible to add light stabilisers or also antioxidants or additionalantioxidants ("Plastics Additives Handbook", Ed. R. Gachter and H.Muller, Hanser Verlag, 3rd edition, 1990; in particular pages 88/89,92,94, 251/252 and 258,259). Likewise it is possible to add furthermodifiers, such as slip agents, mould release agents, impact strengthimprovers, fillers or reinforcing agents such as glass fibres, flameretardants, antistatic agents and, especially for PBT/PC recyclates,modifiers that prevent transesterification during processing.

Particularly suitable stabilisers include:

1. Antioxidants

1.1. Alkylated monophenols, for example2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4,6-dimethylphenol,2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol,2,6-di-tert-butyl-4-isobutylphenol, 2,6-dicyclopentyl-4-methylphenol,2-(α-methylcyclohexyl)-4,6-dimethylphenol,2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol,2,6-di-tert-butyl-4-methoxymethylphenol, 2,6-dinonyl-4-methylphenol,2,4-dimethyl-6-(1'-methylundec-1'-yl)phenol,2,4-dimethyl-6-(1'-methylheptadec-1'-yl)phenol,2,4-dimethyl-6-(1'-methyltridec-1'-yl)phenol and mixtures thereof.

1.2. Alkylthiomethylphenols, for example2,4-dioctylthiomethyl-6-tert-butylphenol,2,4-dioctylthiomethyl-6-methylphenol,2,4-dioctylthiomethyl-6-ethylphenol,2,6-didodecylthiomethyl-4-nonylphenol.

1.3. Hydroquinones and alkylated hydroquinones, for example2,6-di-tert-butyl-4-methoxyphenol, 2,5-di-tert-butylhydroquinone,2,5-di-tert-amylhydroquinone, 2,6-diphenyl-4-octadecyloxyphenol,2,6-di-tert-butylhydroquinone, 2,5-di-tert-butyl-4-hydroxyanisole,3,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyphenylstearate, bis(3,5-di-tert-butyl-4-hydroxyphenyl) adipate.

1.4 Chroman derivatives of formula ##STR16## wherein R is ##STR17##hydrogen, methyl or tert-butyl, e.g. α-tocopherol, β-tocopherol,γ-tocopherol, δ-tocopherol and mixtures thereof (vitamin E).

1.5. Hydroxylated thiodiphenyl ethers, for example2,2'-thiobis(6-tert-butyl-4-methylphenol), 2,2'-thiobis(4-octylphenol),4,4'-thiobis(6-tert-butyl-3-methylphenol),4,4'-thiobis(6-tert-butyl-2-methylphenol),4,4'-thiobis(3,6-di-sec-amylphenol),4,4'-bis(2,6-dimethyl-4-hydroxyphenyl) disulfide.

1.6. Alkylidenebisphenols, for example2,2'-methylenebis(6-tert-butyl-4-methylphenol),2,2'-methylenebis(6-tert-butyl-4-ethylphenol), 2,2'-methylenebis4-methyl-6-(α-methylcyclohexyl)phenol!,2,2'-methylenebis(4-methyl-6-cyclohexylphenol),2,2'-methylenebis(6-nonyl-4-methylphenol),2,2'-methylenebis(4,6-di-tert-butylphenol),2,2'-ethylidenebis(4,6-di-tert-butylphenol),2,2'-ethylidenebis(6-tert-butyl-4-isobutylphenol), 2,2'-methylenebis6-(α-methylbenzyl)-4-nonylphenol!, 2,2'-methylenebis6-(β,β-dimethylbenzyl)-4-nonylphenol!,4,4'-methylenebis(2,6-di-tert-butylphenol),4,4'-methylenebis(6-tert-butyl-2-methylphenol),1,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)butane,2,6-bis(3-tert-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol,1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane,1,1-bis(5-tert-butyl-4-hydroxy-2-methyl-phenyl)-3-n-dodecylmercaptobutane,ethylene glycol bis 3,3-bis(3'-tert-butyl-4'-hydroxyphenyl)butyrate!,bis(3-tert-butyl-4-hydroxy-5-methyl-phenyl)dicyclopentadiene, bis2-(3'-tert-butyl-2'-hydroxy-5'-methylbenzyl)-6-tert-butyl-4-methylphenyl!terephthalate,1,1-bis(3,5-dimethyl-2-hydroxyphenyl)butane,2,2-bis(3,5-di-tert-butyl-4-hydroxyphenyl)propane,2,2-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)-4-n-dodecylmercaptobutane,1,1,5,5-tetra(5-tert-butyl-4-hydroxy-2-methylphenyl)pentane.

1.7. O--, N-- and S---benzyl compounds, for example3,5,3',5'-tetra-tert-butyl-4,4'-hydroxy-dibenzyl ether,octadecyl-4-hydroxy-3,5-dimethylbenzylmercaptoacetate,tris(3,5-di-tert-butyl-4hydroxybenzyl)amine,bis(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dithioterephthalate,bis(3,5-di-tert-butyl-4-hydroxybenzyl)sulfide,isooctyl-3,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate.

1.8. Hydroxybenzylated malonates, for exampledioctadecyl-2,2-bis(3,5-di-tert-butyl-2-hydroxybenzyl)malonate,dioctadecyl-2-(3-tert-butyl-4-hydroxy-5-methylbenzyl)malonate,didodecylmercaptoethyl-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)malonate,bis4-(1,1,3,3-tetramethylbutyl)phenyl!-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)malonate.

1.9. Aromatic hydroxybenzyl compounds, for example1,3,5-tris(3,5-di-tert-butyl-4hydroxybenzyl)-2,4,6-trimethylbenzene,1,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzene,2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)phenol.

1.10. Triazine compounds, for example2,4-bis(octylmercapto)-6-(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine,2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine,2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,3,5-triazine,2,4,6-tris(3,5-di-tert-butyl-4hydroxyphenoxy)-1,2,3-triazine,1,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate,1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate,2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenylethyl)-1,3,5-triazine,1,3,5-tris(3,5-di-tert-butyl-4hydroxyphenylpropionyl)hexahydro-1,3,5-triazine,1,3,5-tris(3,5-dicyclohexyl-4-hydroxybenzyl)isocyanurate.

1.11. Benzylphosphonates, for exampledimethyl-2,5-di-tert-butyl-4-hydroxybenzylphosphonate,diethyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate,dioctadecyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate,dioctadecyl-5-tert-butyl-4-hydroxy-3-methylbenzylphosphonate, thecalcium salt of the monoethyl ester of3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid.

1.12. Acylaminophenols, for example 4-hydroxylauranilide,4-hydroxystearanilide, octylN-(3,5-di-tert-butyl-4-hydroxyphenyl)carbamate. 1.13. Esters ofβ-(3,5-di-tert-butyl-4hydroxyphenyl)propionic acid with mono- orpolyhydric alcohols, e.g. with methanol, ethanol, octadecanol,1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol,neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethyleneglycol, pentaerythritol, tris(hydroxyethyl) isocyanurate,N,N'-bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol,trimethylhexanediol, trimethylolpropane,4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo 2.2.2!octane.

1.14. Esters of β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acidwith mono- or polyhydric alcohols, e.g. with methanol, ethanol,octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol,1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethyleneglycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N'-bis-(hydroxyethyl)oxamide, 3-thiaundecanol,3-thiapentadecanol, trimethylhexanediol, trimethylolpropane,4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo 2.2.2!octane.

1.15. Esters of β-(3.5-dicyclohexyl-4-hydroxyphenyl)propionic acid withmono- or polyhydric alcohols, e.g. with methanol, ethanol octadecanol,1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol,neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethyleneglycol, pentaerythritol, tris(hydroxyethyl) isocyanurate,N,N'-bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol,trimethylhexanediol, trimethylolpropane,4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo 2.2.2!octane.

1.16. Esters of 3.5-di-tert-butyl-4hydroxyphenyl acetic acid with mono-or polyhydric alcohols, e.g. with methanol, ethanol, octadecanol,1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol,neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethyleneglycol, pentaerythritol, tris(hydroxyethyl) isocyanurate,N,N'-bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol,trimethylhexanediol, trimethylolpropane,4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo 2.2.2!octane.

1.17. Amides of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid e.g.N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hexamethylenediamine,N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)trimethylenediamine,N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazine.

Preferred antioxidants are, for example, the following: ##STR18## andthe pentaerythrityl, octyl and the octadecyl ester ofβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid.

2. UV absorbers and light stabilisers

2.1. 2-(2'-Hydroxyphenyl)benzotriazoles, for example2-(2'-hydroxy-5'-methylphenyl)-benzotriazole,2-(3',5'-di-tert-butyl-2'-hydroxyphenyl)benzotriazole,2-(5'-tert-butyl-2'-hydroxyphenyl)benzotriazole,2-(2'-hydroxy-5'-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole,2-(3',5'-di-tert-butyl-2'-hydroxyphenyl)-5-chloro-benzotriazole,2-(3'-tert-butyl-2'-hydroxy-5'-methylphenyl)-5-chloro-benzotriazole,2-(3'-sec-butyl-5'-tert-butyl-2'-hydroxyphenyl)benzotriazole,2-(2'-hydroxy-4'-octyloxyphenyl)benzotriazole,2-(3',5'-di-tert-amyl-2'-hydroxyphenyl)benzotriazole,2-(3',5'-bis-(β,β-dimethylbenzyl)-2'-hydroxyphenyl)benzotriazole,mixture of2-(3'-tert-butyl-2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl)-5-chloro-benzotriazole,2-(3'-tert-butyl-5'-2-(2-ethylhexyloxy)-carbonylethyl!-2'-hydroxyphenyl)-5-chloro-benzotriazole,2-(3'-tert-butyl-2'-hydroxy-5'-(2-methoxycarbonylethyl)phenyl)-5-chloro-benzotriazole,2-(3'-tert-butyl-2'-hydroxy-5'-(2-methoxycarbonylethyl)phenyl)benzotriazole,2-(3'-tert-butyl-2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl)benzotriazole,2-(3'-tert-butyl-5'-2-(2-ethylhexyloxy)carbonylethyl!-2'-hydroxyphenyl)benzotriazole,2-(3'-dodecyl-2'-hydroxy-5'-methylphenyl)benzotriazole, and2-(3'-tert-butyl-2'-hydroxy-5'-(2-isooctyloxycarbonylethyl)phenylbenzotriazole,2,2'-methylene-bis4-(1,1,3,3-tetramethylbutyl)-6-benzotriazole-2-ylphenol!; thetransesterification product of 2-3'-tert-butyl-5'-(2-methoxycarbonylethyl)-2'-hydroxyphenyl!-2H-benzotriazolewith polyethylene glycol 300; R--CH₂ CH₂ --COO(CH₂)₃ .brket close-st.₂,where R=(3'-tert-butyl-4'-hydroxy-5'-2H-benzotriazol-2-yl)phenyl.

2.2. 2-Hydroxybenzophenones, for example the 4-hydroxy, 4-methoxy,4-octyloxy, 4-decyloxy, 4-dodecyloxy, 4-benzyloxy, 4,2',4'-trihydroxyand 2'-hydroxy-4,4'-dimethoxy derivatives.

2.3. Esters of substituted and unsubstituted benzoic acids, as forexample 4-tert-butyl-phenyl salicylate, phenyl salicylate, octylphenylsalicylate, dibenzoyl resorcinol, bis(4-tert-butylbenzoyl) resorcinol,benzoyl resorcinol, 2,4-di-tertbutylphenyl3,5-di-tert-butyl-4-hydroxybenzoate, hexadecyl3,5-di-tert-butyl-4-hydroxybenzoate, octadecyl3,5-di-tert-butyl-4-hydroxybenzoate, 2-methyl-4,6-di-tert-butylphenyl3,5-di-tert-butyl-4-hydroxybenzoate.

2.4. Acrylates, for example ethyl α-cyano-β,β-diphenylacrylate, isooctylα-cyano-β,β-diphenylacrylate, methyl α-carbomethoxycinnamate, methylα-cyano-β-methyl-p-methoxycinnamate, butylα-cyano-β-methyl-p-methoxy-cinnamate, methylα-carbomethoxy-p-methoxycinnamate andN-(β-carbomethoxy-β-cyanovinyl)-2-methylindoline.

2.5. Nickel compounds, for example nickel complexes of 2,2'-thiobis4-(1,1,3,3-tetramethylbutyl)phenol!, such as the 1:1 or 1:2 complex,with or without additional ligands such as n-butylamine, triethanolamineor N-cyclohexyldiethanolamine, nickel dibutyldithiocarbamate, nickelsalts of the monoalkyl esters, e.g. the methyl or ethyl ester, of4-hydroxy-3,5-di-tert-butylbenzylphosphonic acid, nickel complexes ofketoximes, e.g. of 2-hydroxy-4-methylphenyl undecylketoxime, nickelcomplexes of 1-phenyl-4lauroyl-5-hydroxypyrazole, with or withoutadditional ligands.

2.6. Sterically hindered amines, for examplebis(2,2,6,6-tetramethyl-piperidyl)sebacate,bis(2,2,6,6-tetramethyl-piperidyl)succinate,bis(1,2,2,6,6-pentamethylpiperidyl)sebacate,bis(1,2,2,6,6-pentamethylpiperidyl)n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate, the condensate of1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinicacid, the condensate ofN,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and4-tert-octylamino-2,6-dichloro-1,3,5-triazine,tris(2,2,6,6-tetramethyl-4-piperidyl) nitrilotriacetate,tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane-tetracarboxylate,1,1'-(1,2-ethanediyl)bis(3,3,5,5-tetramethylpiperazinone),4-benzoyl-2,2,6,6-tetramethylpiperidine,4-stearyloxy-2,2,6,6-tetramethylpiperidine,bis(1,2,2,6,6-pentamethylpiperidyl)-2-n-butyl-2-(2-hydroxy-3,5-di-tert-butylbenzyl)malonate,3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triazasprio 4.5!decane-2,4-dione,bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)sebacate,bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)succinate, the condensate ofN,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and4-morpholino-2,6-dichloro-1,3,5-triazine, the condensate of2-chloro-4,6-bis(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1,3,5-triazineand 1,2-bis(3-aminopropylamino)ethane, the condensate of2-chloro-4,6-di(4-n-butylamino-1,2,2,6,6-pentamethylpiperidyl)-1,3,5-triazineand 1,2-bis(3-aminopropylamino)ethane,8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro4.5!decane-2,4-dione,3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl)pyrrolidine-2,5-dione,3-dodecyl-1-(1,2,2,6,6-pentamethyl-4-piperidyl)pyrrolidine-2,5-dione.

2.7. Oxamides, for example 4,4'-dioctyloxyoxanilide,2,2'-dioctyloxy-5,5'-di-tert-butoxanilide,2,2'-didodecyloxy-5,5'-di-tert-butoxanilide, 2-ethoxy-2'-ethyloxanilide,N,N'-bis(3-dimethylaminopropyl)oxamide,2-ethoxy-5-tert-butyl-2'-ethoxanilide and its mixture with2-ethoxy-2'-ethyl-5,4'-di-tert-butoxanilide and mixtures of ortho- andparamethoxy-disubstituted oxanilides and mixtures of o- andp-ethoxy-disubstituted oxanilides.

2.8. 2-(2-Hydroxyphenyl)-1.3.5-triazines, for example2,4,6-tris(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine,2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,2,4-bis(2-hydroxy-4-propyloxyphenyl)-6-(2,4-dimethylphenyl)-1,3,5-triazine,2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(4-methylphenyl)-1,3,5-triazine,2-(2-hydroxy-4-dodecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,2-2-hydroxy-4-(2-hydroxy-3-butyloxy-propoxy)phenyl!-4,6-bis(2,4-dimethyl)-1,3,5-triazine,2-2-hydroxy-4-(2-hydroxy-3-octyloxy-propyloxy)phenyl!-4,6-bis(2,4-dimethyl)-1,3,5-triazine.

3. Metal deactivators, for example N,N'-diphenyloxamide,N-salicylal-N'-salicyloyl hydrazine, N,N'-bis(salicyloyl) hydrazine,N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl) hydrazine,3-salicyloylamino-1,2,4-triazole, bis(benzylidene)oxalyl dihydrazide,oxanilide, isophthaloyl dihydrazide, sebacoyl bisphenylhydrazide,N,N'-diacetyladipoyl dihydrazide, N,N'-bis(salicyloyl)oxalyldihydrazide, N,N'-bis(salicyloyl)thiopropionyl dihydrazide.

4. Phosphites and Phosphonites, for example triphenyl phosphite,diphenyl alkyl phosphites, phenyl dialkyl phosphites, tris(nonylphenyl)phosphite, trilauryl phosphite, trioctadecyl phosphite, distearylpentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl) phosphite,diisodecyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite,bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite,bis(isodecyloxy)pentaerythritol diphosphite,bis(2,4-di-tert-butyl-6-methylphenyl)pentaerythritol diphosphite,bis(2,4,6-tris(tert-butylphenyl)pentaerythritol diphosphite, tristearylsorbitol triphosphite,6-isooctyloxy-2,4,8,10-tetra-tert-butyl-12H-dibenzd,g!-1,3,2-dioxaphosphocin,6-fluoro-2,4,8,10-tetra-tert-butyl-12-methyl-dibenzd,g!-1,3,2-dioxaphosphocin,bis(2,4-di-tert-butyl-6-methylphenyl)methylphosphite,bis(2,4-di-tert-butyl-6-methylphenyl)ethylphosphite.

The following phosphites are particularly preferred: ##STR19##

5. Peroxide scavengers, for example esters of β-thiodipropionic acid,for example the lauryl, stearyl, myristyl or tridecyl esters,mercaptobenzimidazole or the zinc salt of 2-mercaptobenzimidazole, zincdibutyldithiocarbamate, dioctadecyl disulfide, pentaerythritoltetrakis(β-dodecylmercapto)propionate.

6. Polyamide stabilisers, for example, copper salts in combination withiodides and/or phosphorus compounds and salts of divalent manganese.

7. Basic co-stabilisers, for example, melamine, polyvinylpyrrolidone,dicyandiamide, triallyl cyanurate, urea derivatives, hydrazinederivatives, amines, polyamides, polyurethanes.

8. Nucleating agents, for example, 4-tert-butylbenzoic acid, adipicacid, diphenylacetic acid, sodium benzoate andaluminium-bis-4-(1,1-dimethylethyl)benzoatehydroxide.

9. Fillers and reinforcing agents, for example, silicates, glass fibres,glass beads, talc, kaolin, mica, barium sulfate, metal oxides andhydroxides, carbon black, graphite.

10. Other additives, for example, plasticisers, lubricants, emulsifiers,pigments such as titanium dioxide, fluorescent whitening agents,flameproofing agents, antistatic agents, blowing agents and, in the caseof recyclate blends, in particular compatibilisers, typicallycopolymers, more particularly block copolymers of styrene with butadieneor of styrene, butadiene and acrylonitrile. These may be copolymers ofethylene and propylene and may contain a third monomer component, e.g.butadiene. Suitable compatibilisers are also chlorinated polyethylene orethylene vinylacetate copolymers, depending on the respectivecomposition of the recyclate. Further suitable compatibilisers contain,in particular, polar groups and are e.g. maleic anhydride styrenecopolymers or graft polymers containing acrylic acid groups. Thepolymeric compatibilisers are usually used in amounts of 2-20% byweight, based on the plastic to be stabilised.

Further additives for epoxy resins are the compounds customarily usedfor curing epoxy resins, e.g. carboxylic anhydrides, polyamines,polythiols, tertiary amines.

11. Benzofuranones and indolinones, for example those disclosed in U.S.Pat. No. 4,325,863, U.S. Pat. No. 4,338,244 or U.S. Pat. Nos. 5,175,312,5,216,052, 5,252,643, DE-A-4 316 611, DE-A-4 316 622, DE-A-4 316 876,EP-A-0 589 839 or EP-A-0 591 102, or 3-4-(2-acetoxyethoxy)phenyl!-5,7-di-tert-butyl-benzofuran-2-one,5,7-di-tert-butyl-3- 4-(2-stearoyloxyethoxy)phenyl!benzofuran-2-one,3,3'-bis 5,7-di-tert-butyl-3-(4-2-hydroxyethoxy!-phenyl)benzofuran-2-one!,5,7-di-tert-butyl-3-(4-ethoxyphenyl)benzofuran-2-one,3-(4-acetoxy-3,5-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one,3-(3,5-dimethyl-4-pivaloyloxyphenyl)-5,7-di-tert-butyl-benzofuran-2-one.

The preferred light stabilisers are those of the classes 2.1, 2.6 and2.7 such as light stabilisers of the Chimassorb® 944, Chimassorb® 119,Tinuvin® 234, Tinuvin® 312, Tinuvin® 622 or Tinuvin® 770 type. Aromaticphosphites or phosphonites are also preferred.

The process can be carried out in any heatable container equipped with astirrer, e.g. in a closed apparatus such as a kneader, mixer or stirredvessel. The process is preferably carried out in an extruder or in akneader. It is immaterial whether processing takes place in an inertatmosphere or in the presence of oxygen.

The polycondensate material to be heated and the diphosphonite or themixture of diphosphonite and difunctional compound are usually put intothe apparatus at the start of the process. However, a subsequentaddition to the polycondensate is also possible. The individualcomponents may also be added in any order. Heating to above the meltingpoint or glass transition temperature is usually effected, withstirring, until the diphosphonite or the mixture of the diphosphoniteand the difunctional compound is homogenised. The temperature isgoverned by the polycondensate employed. In the case of crystallinepolycondendates, processing is preferably carried out in the temperaturerange from melting point to c. 50° C. above the melting point. If thepolycondensates are amorphous, processing is carried out in thetemperature range from c. 50° C. to 150° C. above the respective glasstransition temperature.

Suitable temperatures are, for example, for:

    ______________________________________                                        PA-6              (230-270° C.);                                       PA-6.6            (260-300° C.);                                       PBT               (230-280° C.);                                       PET               (260-310° C.);                                       PBT/PC            (230-280° C.); and                                   PC                (260-320° C.)                                        ______________________________________                                    

For this addition, the diphosphonite and the difunctional compound maybe each independently of the other in the form of liquid, powder,granules or in compacted form or also on a substrate such as silica gel,or together with a polymer powder or wax, e.g. a polyethylene wax, butalso in the form of a masterbatch.

It is preferred to add, per 100 parts of polycondensate, 0.01 to 5 partsof a diphosphonite, or 0.01 to 5 parts of a diphosphonite and 0.01 to 5parts of a difunctional compound. It is particularly preferred to add,per 100 parts of polycondensate, 0.05 to 2 parts of diphosphonite, or0.05 to 2 parts of diphosphonite and 0.1 to 5 parts of difunctionalcompound. It is very particularly preferred to add, per 100 parts ofpolycondensate, 0.1 to 1 part of diphosphonite, or 0.1 to 1 part ofdiphosphonite and 0.1 to 1 part of difunctional compound. The amount ofdiphosphonite and difunctional compound will depend on the initialmolecular weight of the polymer and on the desired final molecularweight. Thus, when using a severely damaged polycondensate, i.e. onehaving a low molecular weight, it is preferred to use diphosphonite or amixture of diphosphonite and the difunctional compound in the upperweight region. But if only a low increase in molecular weight or if onlyprocessing stabilisation is desired, then it is preferred to usediphosphonite or a mixture of diphosphonite and the difunctionalcompound in low concentration.

If the polycondensate is a recyclate, then this may also be used blendedwith virgin material or together with virgin material, typically in acoextrusion process. Blends may typically comprise one componentconsisting of virgin material and the other of recyclate. Astabilisation/increase in the molecular weight may in this case becarried out independently of each other.

This invention also relates to the use of a diphosphonite for increasingthe molecular weight of virgin polyamide or virgin polyester, polyamiderecyclates or polyester recyclates. The preferred embodiments of the usecorrespond to those of the process.

In another of its aspects, the invention relates to the use of a mixturecomprising a diphosphonite and a difunctional compound selected from theclass of the diepoxides, bismaleimides, tetracarboxylic dianhydrides,bisoxazolines, bisoxazines, bisacyl lactams and diisocyanates forincreasing the molecular weight of virgin polyamide, virgin polyester orvirgin polycarbonate, or polyamide recyclates, polyester recyclates orpolycarbonate recyclates. The preferred embodiments of the usecorrespond to those of the process.

The invention also relates to a mixture comprising a polycondensate, adiphosphonite and a difunctional compound selected from the class of thediepoxides, bismaleimides, tetracarboxylic dianhydrides, bisoxazolines,bisoxazines, bisacyl lactams and diisocyanates. The preferredembodiments of the mixtures correspond to those of the process.

The invention is illustrated by the following non-limitative Examples inwhich and in the remainder of the description, unless otherwise stated,parts and percentages are by weight.

EXAMPLE 1-7

In a Brabender plastograph equipped with a W 50 mixing chamber,polyamide 6 (Durethan® B30 S, supplied by Bayer; predried overnight at80° C. in a vacuum drying oven), is kneaded under nitrogen at 235° C.and 40 rpm over 30 minutes and the torque is determined. Subsequentlythe melt volume rate (MVR) is determined. The values listed in Table 1are obtained.

                  TABLE 1                                                         ______________________________________                                        Increase in molecular weight of polyamide                                     Irgafos PEPQ  Difunct. cmpd                                                                             Torque after                                                                             MVR                                      (parts per 100                                                                              (parts per 100                                                                            10 or 30 min.                                                                             cm.sup.3 /                              parts of polymer)                                                                           parts of polymer)   Nm!  10 min!                                ______________________________________                                        Ex. 1     1.0     Irgafos                                                                             --   --     5.1  7.2   14.2                                             PEPQ                                                            2     2.0     "     --   --     5.2  14.2  7.6                                3     1.0     "     1.0  epoxide 1                                                                            8.6  11.0  5.9                                4     1.0     "     1.0  epoxide 2                                                                            20.8 24.0  6.0*                               5     0.5     "     0.5  epoxide 3                                                                            9.4  14.7  n.d.                               6     2.0     "     2.0  epoxide 1                                                                            13.1 20.6  n.d.                               7     0.5     "     0.5  BMI 1  8.3  9.1   n.d.                               V1    --      --    --   --     3.7  4.0   44.5                               V2    --      --    1.0  epoxide 1                                                                            6.3  5.6   18.7                           ______________________________________                                         *: at 235° C./10 kg; n.d.: not determined                         

The increase of the torque and the decrease of the melt volume rate(determined in general accordance with ISO 1133; 235° C./2.16 kg) show amarked increase in molecular weight in the samples of Examples 1 to 7,treated according to the practice of this invention, over the comparisonExamples (V1 and V2).

EXAMPLE 8:

In a Brabender plastograph equipped with a W 50 mixing chamber, a PBT/PCblend (Pocan®, supplied by Bayer) is kneaded at 235° C. and 46 rpm over30 minutes, and the melt volume rate is determined in general accordancewith ISO 1133; 235° C./2.16 kg.

When 0.25% of Irgafos PEPQ and 0.5% of p-phenylenebisoxazoline are addedto the blend, the MVR value is 9.2 cm³ /10 min. Without additives, a MVRvalue of 10.5 cm³ /10 min. is obtained. The initial value is 10.0 cm³/10 min.

EXAMPLES 9-41

In general accordance with Examples 1 to 7, Durethan B 30 S is kneadedin air at 235° C. and 40 rpm over 30 minutes, and the torque and the MVRare then determined in general accordance with ISO 1133; 235° C./2.16kg.

    __________________________________________________________________________                                Torque        MVR                                                  Difunct. compound                                                                         Nm!          (235° C./2.16 kg)            Examples                                                                              Irgafos PEPQ                                                                           (epoxide)  after 10                                                                             30 min  cm.sup.3 /10                       __________________________________________________________________________                                              min!                                 9      3.00 Irg. PEPQ                                                                         --         4.9    20.7   2.3                                 10      0.50 Irg. PEPQ                                                                         0.5 Araldit GT 6084                                                                      4.2    6.8    9.3                                 11      1.00 Irg. PEPQ                                                                         1.0 Araldit GT 6084                                                                      4.6    8.3    6.2                                 12      0.25 Irg. PEPQ                                                                         0.25 Araldit PY 306                                                                      6.0    9.3    9.6                                 13      0.50 Irg. PEPQ                                                                         0.50 Araldit PY 306                                                                      7.2    10.3   5.6                                 14      1.00 Irg. PEPQ                                                                         1.00 Araldit PY 306                                                                      15.7   23.5   2.0                                 15      0.25 Irg. PEPQ                                                                         1.00 Araldit PY 306                                                                      16.0   16.8   2.2                                 16      0.10 Irg. PEPQ                                                                         1.00 Araldit PY 306                                                                      14.4   14.7   3.8                                 17      1.00 Irg. PEPQ                                                                         1.00 Araldit CY 179                                                                      9.9    11.2   6.6                                 18      1.00 Irg. PEPQ                                                                         0.50 Araldit CY 179                                                                      5.2    8.3    10.7                                19      0.50 Irg. PEPQ                                                                         1.00 Araldit CY 179                                                                      9.2    10.2   7.9                                 20      2.00 Irg. PEPQ                                                                         0.50 Araldit CY 179                                                                      6.1    13.5   6.6                                 21      0.10 Irg. PEPQ                                                                         0.10 Araldit PY 284                                                                      3.4    5.1    14.3                                22      0.25 Irg. PEPQ                                                                         0.25 Araldit PY 284                                                                      4.1    6.3    11.0                                23      0.50 Irg. PEPQ                                                                         0.50 Araldit PY 284                                                                      5.1    8.1    7.5                                 24      1.00 Irg. PEPQ                                                                         1.00 Araldit PY 284                                                                      8.0    10.0   5.8                                 25      2.00 Irg. PEPQ                                                                         0.50 Araldit PY 284                                                                      4.7    13.8   4.7                                 __________________________________________________________________________                                        Torque after                                                                          MVR                                           Difunct. compound        Nm!    (235° C./2.16 kg)          Examples                                                                           Irg. PEPQ                                                                            (epoxy resin)                                                                              Further additives                                                                        10 min                                                                            30 min                                                                             cm.sup.3 /10                     __________________________________________________________________________                                                min!                              26   1.00 Irg. PEPQ                                                                       1.00 Araldit PY 306                                                                        0.25% Irgafos 168                                                                        15.3                                                                              21.8                                                                              1.9                               27   1.00 Irg. PEPQ                                                                       1.00 Araldit PY 306                                                                        0.25% Irganox 3114                                                                       14.3                                                                              22.0                                                                              0.4                               28   1.00 Irg. PEPQ                                                                       1.00 Araldit PY 306                                                                        0.25% Irganox 1019                                                                       16.3                                                                              22.1                                                                              0.3                               29   0.50 Irg. PEPQ                                                                       0.50 Araldit GT 6071                                                                       0.25% Irgafos 12                                                                         5.1 10.0                                                                              5.1                               30   0.50 Irg. PEPQ                                                                       0.50 Araldit GT 6071                                                                       0.25% Z-1  5.1 10.7                                                                              4.6                               31   0.50 Irg. PEPQ                                                                       0.50 Araldit PY 306                                                                        0.25% dicyandiamide                                                                      8.8 13.2                                                                              3.1                               32   0.50 Irg. PEPQ                                                                       0.50 Araldit PY 306                                                                        0.125% Irganox B 225                                                                     6.3 10.3                                                                              4.6                                                        0.100% CaO                                                                    0.025% calcium stearate                              33   0.50 Irg. PEPQ                                                                       0.50 Araldit PY 306                                                                        0.25% Z-2  7.4 9.6 4.9                               34   0.25 Irg. PEPQ                                                                       0.25 Araldit PY 306                                                                        0.25% Irganox 1098                                                                       5.1 7.5 8.7                               35   0.25 Irg. PEPQ                                                                       0.25 Araldit PY 306                                                                        0.25% Irganox 1098                                                                       5.1 7.3 8.9                                                        0.25% Tinuvin 622                                    36   0.5 Irg. PEPQ                                                                        0.5% Araldit PY 306     7.7 9.3 4.7                                           0.25% Epiclone B 4400                                             __________________________________________________________________________                                        Torque after                                                                          MVR                                                                    Nm!    (235° C./2.16 kg)          Examples                                                                           Irg. PEPQ                                                                            Difunct. compound                                                                          Further additives                                                                        10 min                                                                            30 min                                                                             cm.sup.3 /10                     __________________________________________________________________________                                                min!                              37   1.0 Irg. PEPQ                                                                        1.0% p-phenylenebisoxazoline                                                               --         6.3 11.8                                                                              3.4                               38   0.5 Irg. PEPQ                                                                        0.5% p-phenylenediisocyanate                                                               --         5.5 6.8 9.8                               39   0.5 Ing. PEPQ                                                                        1.0% p-phenylenediisocyanate                                                               --         6.0 7.4 8.6                               40   1.0 Irg. PEPQ                                                                        1.0% p-phenylenediisocyanate                                                               --         6.7 9.4 6.3                               41   0.5 Irg. PEPQ                                                                        0.5% p-phenylenediisocyanate                                                               --         11.2                                                                              16.3                                                                              2.0                                           0.5 Araldit PY 306                                                __________________________________________________________________________

EXAMPLE 42 COMPARISON EXAMPLE 3

In general accordance with Examples 1-7, filled polyamide 6 (DurethanB/BKV 30 H; containing 30% of glass fibres) is kneaded at 235° C. and 40rpm over 30 minutes. The torque is 17.3 Nm (without additives: 9.9)after 30 min and with the addition of 1.0% of Irgafos PEPQ and 1% ofAraldit PY 306. The MVR value (235° C./2.16 kg) is 2.5 cm³ /10 min(without additives: 3.8 cm³ /10 min).

EXAMPLE 42 COMPARISON EXAMPLE 4

Polyamide 6 damaged by storing in water (10 weeks/80° C.) is compounded,after drying overnight at 80° C. in a vacuum drying oven, on atwin-screw extruder (CW 100, supplied by Haake) at 240° C. Test samplesare prepared from the extrudate at 250° C. on an injection mouldingmachine type Arburg 221 and, inter alia, the mechanical properties aredetermined in the freshly moulded state.

    ______________________________________                                                   DIN 53455           DIN 53448                                                        Tear   ISO 180/1A                                                                              Tensile                                               Tensile                                                                              resis- Impact    impact                                                strength                                                                             tance  strength  strength                                               N/mm.sup.2 !                                                                         %!    notched    kJ/m.sup.2 !                              ______________________________________                                        Comparison Example 4                                                                       78.8     30.3   8.9     208                                      (no additives)                                                                Example 43   78.7     57.9   10.0    236                                      (addition of                                                                  0.25% Irgafos PEPQ                                                            0.25% Araldit GT 6071)                                                        ______________________________________                                    

EXAMPLE 44 COMPARISON EXAMPLE 5

Polyamide 66 scrap material (mechanically stripped, from wheel shields/30% mineral filling) is extruded, after drying overnight at 80° C. in avacuum drying oven, on a twin-screw extruder (TW 100, supplied by Haake)at 290° C. and 30 rpm. Test samples are prepared from the extrudate at260° C. on an injection moulding machine type Arburg 221 and, interalia, the tensile impact strength is determined according to DIN 53448(average of 5 samples) in the freshly moulded state.

    ______________________________________                                        Comparison Example 5   365 kJ/m.sup.2                                         (no additives)                                                                Example 44             430 kJ/m.sup.2                                         (addition of                                                                  0.25% Irgafos PEPQ                                                            0.25% Araldit PY 306)                                                         ______________________________________                                    

EXAMPLE 45 COMPARISON EXAMPLE 6

PBT/PC grinding stock (production waste of car bumpers) is kneaded at235° C. and 40 rpm over 30 minutes and, inter alia, the indicated valuesare determined.

    ______________________________________                                                      Torque after                                                                             MVR                                                                       30 min  (250° C./2.16 kg)                                       15 min  Nm!     cm.sup.3 /10 min!                               ______________________________________                                        Comparison Example 6                                                                          3.8      2.6     29.0                                         (no additives)                                                                Example 45      3.9      3.6     17.3                                         (1% Irgafos PEPQ                                                              0.25% pyromellitic dianhydride)                                               ______________________________________                                    

The following compounds are used: ##STR20## Irgafos® 168 (ciba; CH):tris(2,4-di-tert-butylphenyl)phosphite

Irganox® 225 (ciba; CH): 1:1 mixture of the pentaerythrityl ester ofβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid andtris(2,4-di-tert-butylphenyl)phosphite

Irganox® 1019 (ciba; CH):N,N'-trimethylene-bis-3-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionate

Irganox® 1098 (ciba; CH):N,N'-hexamethylene-bis-3-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionate

Irganox® 3114 (ciba; CH):1,3,5-tris(3',5'-di-tert.-butyl-4'-hydroxybenzyl)-isocyanurate

Tinuvin® 622 (ciba; CH): polymer of butanedioic acid with4-hydroxy-2,2,6,0-tetramethylpiperidine ethanol ##STR21##

What is claimed is:
 1. A process for increasing the molecular weight ofpolycondensates, essentially without crosslinking, which comprisesheating a polyamide, a polyester, a polycarbonate, or a copolymer or ablend of these polymers, with the addition of at least one diphosphoniteand at least one difunctional compound selected from the groupconsisting of the diepoxides, bismaleimides, tetracarboxylicdianhydrides, bioxazolines, bisoxazines, bisacyl lactams anddiisocyanates to above the melting point (in the case of crystallinepolycondensate types) or to above the glass transition temperature (inthe case of amorphous polycondensate types) of the polymer.
 2. A processaccording to claim 1, wherein the polycondensate is a polycondensaterecyclate.
 3. A process according to claim 1, wherein the diepoxide is acompound containing epoxy radicals of formula (II)which radicals arelinked direct to carbon, oxygen, nitrogen or sulfur atoms, wherein R₁and R₃ are both hydrogen, R₂ is hydrogen or methyl, and n=0, or whereinR₁ and R₃, taken together, are --CH₂ --CH₂ -- or --CH₂ --CH₂ --CH₂ --,in which case R₂ is hydrogen and n=0 or
 1. 4. A process according toclaim 1, wherein the bismaleimide is a compound of formula (III)##STR22## wherein R is an aliphatic, aromatic, cycloaliphatic orheterocyclic radical; and R' and R" are each independently of the otherhydrogen, C₁ -C₄ alkyl, C₁ -C₆ alkoxy, phenyl or phenyloxy.
 5. A processaccording to claim 1, wherein the tetracarboxylic dianhydride is acompound of formula (IV) ##STR23## wherein R°° is a radical of formulae(Va)-(Vl) ##STR24## wherein Q is --CH₂ --, --CH(CH₃)--, --C(CH₃)₂ --,--C(CF₃)₂ --, --S--, --O--, --(O)S(O)--, --NHCO--, --CO-- or --P(O)(C₁-C₂₀ alkyl)--, and the aromatic rings in formulae (Va)-(Ve) and (Vk) areunsubstituted or substituted by one or more than one C₁ -C₆ alkyl group,C₁ -C₆ alkoxy group or halogen atom.
 6. A process according to claim 1,wherein the bisoxazoline is a compound of formula (VI) ##STR25## whereinR₅, R₆, R₇ and R₈ are each independently of one another hydrogen,halogen, alkyl, cycloalkyl, aryl, alkoxy or carboxyalkyl, and X° is anaromatic radical.
 7. A process according to claim 1, wherein thebisoxazine is a compound of formula (VII) ##STR26## wherein R₉, R₁₀,R₁₁, R₁₂, R₁₃ and R₁₄ are each independently of one another hydrogen,halogen, alkyl, cycloalkyl, aryl, alkoxy or carboxyalkyl, and X°° is anaromatic radical.
 8. A process according to claim 1, wherein the bisacyllactam is a compound of formula (VIII) ##STR27## wherein q is 1 or 2,and Q° is an aromatic radical of the formulae: ##STR28## wherein X isone of the radicals --CH₂ --, --C(O)--, --P(O)(C₁ --C₁₈ alkyl)--,--(O)S(O)--, --O-- or --S--.
 9. A process according to claim 1, whereinthe diisocyanate is a compound of formula (IX)

    O═C═N--R.sub.15 --N═C═O                    (IX)

wherein R₁₅ is C₁ -C₂₀ alkylene or polymethylene, arylene, aralkylene orcycloalkylene.
 10. A process according to claim 1, which comprisesadding 0.01 to 5 parts of the diphosphonite and 0.01 to 5 parts of thedifunctional compound per 100 parts of polycondensate.
 11. A processaccording to claim 1 wherein the polycondensate used is a poly(butyleneterephthalate) polycarbonate blend or a blend containing mainlypoly(butylene terephthalate)/polycarbonate or a corresponding recyclateor a blend of a recyclate and a virgin plastic.
 12. A process accordingto claim 1, wherein the polycondensate used is a polycarbonate or acorresponding recyclate or a blend of a recyclate and a virgin plastic.13. A process according to claim 1, wherein the polycondensate used is apoly(ethylene terephthalate) or a corresponding recyclate or a blend ofa recyclate and a virgin plastic.
 14. A mixture comprising adiphosphonite, a difunctional compound selected from the groupconsisting of the diepoxides, bismaleimides, tetracarboxylicdianhydrides, bioxazolines, bisoxazines, bisacyl lactams anddiisocyanates, and a virgin polycondensate or polycondensate recyclateor a mixture of a recyclate and a virgin plastic.
 15. A polycondensateobtained according to a process as claimed in claim
 1. 16. A processaccording to claim 1, wherein the diphosphonite is a compound of formula##STR29## wherein R° is one to five C₁ -C₈ alkyl radicals; X'is aradical ##STR30## and X is a direct bond, --(O)S(O)--, --C(O)--, --S--,--O-- or arylene.